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- Number of terms: 20560
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Tektronix provides test and measurement instruments, solutions and services for the computer, semiconductor, military/aerospace, consumer electronics and education industries worldwide.
A transducer which converts sound pressure waves into electrical signals.
Industry:Software
The composite analog television signal’s amplitude can be described in volts or IRE units with 140 IRE representing a full amplitude composite analog signal. The 0 IRE point is at blanking level, with sync tip at –40 IRE and white extending to +100 IRE In the studio, the composite analog video signal is typically 1 volt in amplitude.
Thus in the studio, 1 IRE is equal to 1/140 of a volt or 7.14 mV. IRE stands for Institute of Radio Engineers, the organization which defined the unit.
Industry:Software
In an image coding system that derives a luminance signal and two bandwidth-limited color-difference signals, constant luminance prevails if all of the luminance information is encoded into one signal that is supplemented by but totally independent of two color signals carrying only chrominance information, e.g., hue and saturation.
Constant luminance is only achieved when the luminance and chrominance vectors are derived from linear signals. The introduction of nonlinear transform characteristics (usually for better signal-to-noise and control of dynamic range prior to bandwidth reduction) before creating the luminance and chrominance vectors destroys constant luminance. Current video systems do not reconstitute the luminance and chrominance signals in their linear form before further processing and, therefore, depart from constant luminance. Note: When R, G, B information is required to be recovered from the set of luminance and color-difference signals, the values correlated to the original signals are obtained only if the luminance and chrominance signals have been derived from the linear functions of R, G, B or have been transformed back to linear. Constant luminance not only provides a minimum of subjective noise in the display (since the luminance channel does not respond to chrominance noise), but also preserves this noise minimum through chrominance transformations.
Industry:Software
Method of scanning video in which the entire frame is scanned at once rather than interleaved. The rate of scan must be fast enough that the average light level of the scene does not decrease between scans and cause flicker. Another term for a noninterlaced system is progressive scan.
Industry:Software
a) A luminance key mode which inverts the polarity of the key source to allow dark areas of the source video to cut holes in background instead of bright areas. b) A chroma key mode which inverts the foreground and background positions.
Industry:Software
In order to obtain the highest quality output signal from a microphone, a preamplifier input should provide a load (impedance) which exactly matches a microphone’s output impedance.
Microphone output impedances vary from 150 ohms to several megohms.
Industry:Software
Single command within a program. Instructions may be arithmetic or logical, may operate on registers, memory, or I/O devices, or may specify control operations. A sequence of instructions is a program.
Industry:Software
a) Luminance has technical as well as colloquial definitions. The generic flux from a light-emitting or lightreflecting surface; the subjective response to luminance is brightness. The quotient of the luminous flux at an element of the surface surrounding the point and propagated in directions defined by an elementary cone containing the given direction, by the product of the solid angle of the cone and the area of the orthogonal projection of the element of the surface on a plane perpendicular to the given direction. b) The luminous flux may be leaving, passing through, and arriving at the surface or both. The luminance for each element of a surface within the field of view is defined as the ratio of luminous flux per solid angle to the unit projected area of the surface. Units are candelas per square meter, foot lamberts, nits.
Industry:Software
Coding of a macroblock or picture that uses information both from itself and from macroblocks and pictures occurring at other times.
Industry:Software
The term used to describe a subject’s main source of illumination.
When shooting outdoors, the key light is usually the sun.
Industry:Software
